Abstract: Fibrinolytic enzyme plays an important role in thrombolytic therapy,and they can dissolve fibrin which is the main components of blood clots.The encoding sequence of fibrinolytic enzyme from Arenicola cristata were amplified by RACE from digestive tract tissues of A.cristata. The prokaryotic expression vector of the gene was constructed and fusion protein was then induced to express in E.coli. Plasminogen activator activity of the fusion protein purified by the Ni²⁺ resin column was detected by fibrin plate method.Thus,the cDNA sequence and amino acid sequence of fibrinolytic enzyme from A.cristata were obtained.The recombinant expression vector pET-21a-AFE was successfully constructed.The purified fusion protein can dissolve fibrin by activating plasminogen.In short,the cDNA sequence and amino acid sequence of fibrinolytic enzyme from A.cristata were obtained.This enzyme was preliminarily proved to have plasminogen activation activity,and might act as a thrombolytic agent for use in thrombosis.

Key words: Arenicola cristata, fibrinolytic enzyme, RACE, gene sequence